Scripting IvyGen with Python
You can call the ivy_gen operator with specific values for all the parameters you would later edit in the context menu: 

bpy.ops.curve.ivy_gen(
    maxIvyLength         = 1,
    primaryWeight        = 0.5,
    randomWeight         = 0.2,
    gravityWeight        = 1,
    adhesionWeight       = 0.1,
    branchingProbability = 0.05,
    leafProbability      = 0.35,
    ivySize              = 0.02,
    ivyLeafSize          = 0.02,
    ivyBranchSize        = 0.001,
    maxFloatLength       = 0.5,
    maxAdhesionDistance  = 1,
    randomSeed           = 0,
    maxTime              = 0,
    growLeaves           = True,
    updateIvy            = False
)


To fully automate this, all you need to do prior to calling this operator is to place the 3D cursor where you want your ivy to start growing:

bpy.context.scene.cursor_location = (x,y,z)

And to also select the object you want to grow your ivy on:

bpy.context.scene.objects['MyObject'].select = True
bpy.context.scene.objects.active             = bpy.context.scene.objects['MyObject']